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Experimental changes that cause SQLite to use bytes 28..31 of the database

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header to determine the database size, rather than using the actual database
size.  This allows database space to be preallocated.

FossilOrigin-Name: b844ac6fcb72595a71e5c5283ec461309a87ba79
This commit is contained in:
drh
2010-03-27 17:12:36 +00:00
parent c26c00495f
commit dd3cd977cc
7 changed files with 71 additions and 55 deletions
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65
src/btree.c
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@@ -516,11 +516,8 @@ static void invalidateIncrblobCursors(
static int btreeSetHasContent(BtShared *pBt, Pgno pgno){
int rc = SQLITE_OK;
if( !pBt->pHasContent ){
int nPage = 100;
sqlite3PagerPagecount(pBt->pPager, &nPage);
/* If sqlite3PagerPagecount() fails there is no harm because the
** nPage variable is unchanged from its default value of 100 */
pBt->pHasContent = sqlite3BitvecCreate((u32)nPage);
assert( pgno<=pBt->nPage );
pBt->pHasContent = sqlite3BitvecCreate(pBt->nPage);
if( !pBt->pHasContent ){
rc = SQLITE_NOMEM;
}
@@ -1564,12 +1561,8 @@ static MemPage *btreePageLookup(BtShared *pBt, Pgno pgno){
** error, return ((unsigned int)-1).
*/
static Pgno pagerPagecount(BtShared *pBt){
int nPage = -1;
int rc;
assert( pBt->pPage1 );
rc = sqlite3PagerPagecount(pBt->pPager, &nPage);
assert( rc==SQLITE_OK || nPage==-1 );
return (Pgno)nPage;
int nPage = (int)pBt->nPage;
return nPage;
}
/*
@@ -2254,8 +2247,8 @@ static int lockBtree(BtShared *pBt){
/* Do some checking to help insure the file we opened really is
** a valid database file.
*/
rc = sqlite3PagerPagecount(pBt->pPager, &nPage);
if( rc!=SQLITE_OK ){
nPage = get4byte(28+(u8*)pPage1->aData);
if( nPage==0 && (rc = sqlite3PagerPagecount(pBt->pPager, &nPage))!=0 ){
goto page1_init_failed;
}else if( nPage>0 ){
int pageSize;
@@ -2333,6 +2326,7 @@ static int lockBtree(BtShared *pBt){
pBt->minLeaf = (pBt->usableSize-12)*32/255 - 23;
assert( pBt->maxLeaf + 23 <= MX_CELL_SIZE(pBt) );
pBt->pPage1 = pPage1;
pBt->nPage = nPage;
return SQLITE_OK;
page1_init_failed:
@@ -2370,12 +2364,10 @@ static int newDatabase(BtShared *pBt){
MemPage *pP1;
unsigned char *data;
int rc;
int nPage;
assert( sqlite3_mutex_held(pBt->mutex) );
rc = sqlite3PagerPagecount(pBt->pPager, &nPage);
if( rc!=SQLITE_OK || nPage>0 ){
return rc;
if( pBt->nPage>0 ){
return SQLITE_OK;
}
pP1 = pBt->pPage1;
assert( pP1!=0 );
@@ -2401,6 +2393,8 @@ static int newDatabase(BtShared *pBt){
put4byte(&data[36 + 4*4], pBt->autoVacuum);
put4byte(&data[36 + 7*4], pBt->incrVacuum);
#endif
pBt->nPage = 1;
data[31] = 1;
return SQLITE_OK;
}
@@ -2769,12 +2763,12 @@ static int allocateBtreePage(BtShared *, MemPage **, Pgno *, Pgno, u8);
*/
static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg){
Pgno nFreeList; /* Number of pages still on the free-list */
int rc;
assert( sqlite3_mutex_held(pBt->mutex) );
assert( iLastPg>nFin );
if( !PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg!=PENDING_BYTE_PAGE(pBt) ){
int rc;
u8 eType;
Pgno iPtrPage;
@@ -2850,7 +2844,7 @@ static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg){
while( iLastPg==PENDING_BYTE_PAGE(pBt)||PTRMAP_ISPAGE(pBt, iLastPg) ){
if( PTRMAP_ISPAGE(pBt, iLastPg) ){
MemPage *pPg;
int rc = btreeGetPage(pBt, iLastPg, &pPg, 0);
rc = btreeGetPage(pBt, iLastPg, &pPg, 0);
if( rc!=SQLITE_OK ){
return rc;
}
@@ -2863,6 +2857,7 @@ static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg){
iLastPg--;
}
sqlite3PagerTruncateImage(pBt->pPager, iLastPg);
pBt->nPage = iLastPg;
}
return SQLITE_OK;
}
@@ -2886,6 +2881,10 @@ int sqlite3BtreeIncrVacuum(Btree *p){
}else{
invalidateAllOverflowCache(pBt);
rc = incrVacuumStep(pBt, 0, pagerPagecount(pBt));
if( rc==SQLITE_OK ){
rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
put4byte(&pBt->pPage1->aData[28], pBt->nPage);
}
}
sqlite3BtreeLeave(p);
return rc;
@@ -2941,11 +2940,12 @@ static int autoVacuumCommit(BtShared *pBt){
rc = incrVacuumStep(pBt, nFin, iFree);
}
if( (rc==SQLITE_DONE || rc==SQLITE_OK) && nFree>0 ){
rc = SQLITE_OK;
rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
put4byte(&pBt->pPage1->aData[32], 0);
put4byte(&pBt->pPage1->aData[36], 0);
put4byte(&pBt->pPage1->aData[28], nFin);
sqlite3PagerTruncateImage(pBt->pPager, nFin);
pBt->nPage = nFin;
}
if( rc!=SQLITE_OK ){
sqlite3PagerRollback(pPager);
@@ -3269,6 +3269,7 @@ int sqlite3BtreeSavepoint(Btree *p, int op, int iSavepoint){
rc = sqlite3PagerSavepoint(pBt->pPager, op, iSavepoint);
if( rc==SQLITE_OK ){
rc = newDatabase(pBt);
pBt->nPage = get4byte(28 + pBt->pPage1->aData);
}
sqlite3BtreeLeave(p);
}
@@ -4833,32 +4834,32 @@ static int allocateBtreePage(
}else{
/* There are no pages on the freelist, so create a new page at the
** end of the file */
int nPage = pagerPagecount(pBt);
*pPgno = nPage + 1;
if( *pPgno==PENDING_BYTE_PAGE(pBt) ){
(*pPgno)++;
}
rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
if( rc ) return rc;
pBt->nPage++;
if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ) pBt->nPage++;
#ifndef SQLITE_OMIT_AUTOVACUUM
if( pBt->autoVacuum && PTRMAP_ISPAGE(pBt, *pPgno) ){
if( pBt->autoVacuum && PTRMAP_ISPAGE(pBt, pBt->nPage) ){
/* If *pPgno refers to a pointer-map page, allocate two new pages
** at the end of the file instead of one. The first allocated page
** becomes a new pointer-map page, the second is used by the caller.
*/
MemPage *pPg = 0;
TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", *pPgno));
assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
rc = btreeGetPage(pBt, *pPgno, &pPg, 0);
TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", pBt->nPage));
assert( pBt->nPage!=PENDING_BYTE_PAGE(pBt) );
rc = btreeGetPage(pBt, pBt->nPage, &pPg, 0);
if( rc==SQLITE_OK ){
rc = sqlite3PagerWrite(pPg->pDbPage);
releasePage(pPg);
}
if( rc ) return rc;
(*pPgno)++;
if( *pPgno==PENDING_BYTE_PAGE(pBt) ){ (*pPgno)++; }
pBt->nPage++;
if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ){ pBt->nPage++; }
}
#endif
put4byte(28 + (u8*)pBt->pPage1->aData, pBt->nPage);
*pPgno = pBt->nPage;
assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
rc = btreeGetPage(pBt, *pPgno, ppPage, 0);